Fig. 2 shows the designed rotator of the left-right snow blade. Most snowplow blade rotations are a manual hydraulic system with an operator pulling a lever to push the blade out of the car in order to change the blade direction. In the case of the hydraulic system, the rotating speed is too slow due to the heavy weight and the hydraulic fluid temperature dropping in winter as well as the front of the vehicle frequently striking the ground due to the heavy weight of a hydraulic type snowplow. In the case of a wire type snowplow, after a period of time of use, cutting and breakage of the wire occurs due to wire fatigue. The way to solve this problem is through the new design developed in the present study with a specific explanation shown in Fig. 2.

Fig. 2 
Schematic design of left-right rotator

As shown in Fig. 2, the rotator of the left-right snow blade consists of many parts such as the separation prevention roller, rotator stopper, rotation angle location control sensor, left-right rotating motor, sprocket groove, sensor plate of the rotational angle position control and the rotational shaft used for protecting against impact shock, similar to an automated driven motor, in order to absorb any external impact. Here, the rotational shaft for protecting against impact shock acts like an automotive clutch that serves to either transmit or block the power when there is an abnormal shock from the snow blade. This design is the focus of the present study and Fig. 3 shows the detailed drawing depicting the rotational shaft.

Fig. 3 
Rotational shaft detail diagram for protecting impact shock

Fig. 4 shows a detailed explanation for the operating principal of the bobbin as an automotive clutch as shown in Fig. 3. As shown in Fig. 4, the clutch bobbin is connected to the motor connection part and engages with the snowplow rotating shaft connected gear. While the gear is engaged with another gear rotation, in the event of external shocks arising the from snowplow, the engaged gears are deviated from the push spring. Therefore, though the rotation shaft is rotating to the impact direction, the motor is not rotating because the rotation is not transmitted to the motor by a clutch interception, protecting the motor. This is the core principle of the present study.

Fig. 4 
Clutch bobbin operating principle for impact shock absorption

Fig. 5 shows the height adjusting design between the snowplow and vehicle. When the snowplow is mounted to the vehicle, if the snowplow has no height adjusting function, the snowplow mounting is not easy. In addition, a change in the vehicle height can occur following a period of use and cargo weight deformation. To solve this problem, the Fig. 5 design was developed. Through this design, it can easily match the height pitch when mounting the snowplow to the vehicle. If the holes were perforated at the end of the triangular bracket attached to the back plate bracket, the height could be adjusted easily.

Fig. 5 
Mounting height adjustment design

Fig. 6 shows the designed rotator used in order to prevent front and rear rolling deformation. Folding a flat plate twice by 90 degrees to increase stiffness protects deflection; and both nuts and bolts are securely tightened to this arms.

Fig. 6 
Front-rear rolling deflection protection design of the snowplow rotator

The front-rear rolling deflection protection design was changed as shown in Fig. 7. As shown in the figure, piece No. ① was added to piece No. ②. Fig. 8 shows the boundary conditions of the computer simulation. A load of 500 N was given on both ends of the protection member and fixing points are shown. The simulation was conducted by using Nastran-101 (statistical analysis), a well-known commercially used program. The analysis results for before and after design changes were compared, as shown in Figs. 9(a) and 9(b) and include the analysis models. Table 1 summarizes the analysis results of Fig. 9. As shown in Table 1, the maximum deflection was 1.85 mm before the design change. However, it was lowered about 0.03 mm after design modification in the same loading conditions. Through this, it was found that the deflection degree improves about 62 times. Indicating that the initial protection member model was changed from “ㄴ” type shape to “ㄷ” type shape like box type in order to have higher rigidity.

Fig. 7 
Cross section region and its magnified shape

Fig. 8 
Loads and boundary conditions of snowplow in a static simulation

Fig. 9 
Structural analysis results of snowplow (a) current model and (b) modified model

Through this design change, the snow removal operation is easy and safe because of increased rigidity and durability when a collision.

The conventional assembly method between a snowplow and vehicle is used with a hole and pin method in that the hole is mounted on the snowplow and a pin is mounted on the vehicle front as shown in Fig. 10(a). This approach is dangerous when in a collision because the pin is extruded. To solve this problem, the design of the pin mounted to the snowplow is proposed in the present study as shown in Fig. 10(b).

Fig. 10 
Snowplow mounting method to the vehicle, (a) conventional method and (b) newly designed method

Fig. 11 shows the detailed explanation of the assembly method of Fig. 10. As shown in Fig. 11, it is safe to insert a pin across the vehicle equipped with a snowplow.

Fig. 11 
Explanation of mounting method between snowplow and vehicle

Fig. 12 shows the explanation for the moving die design mounting method use between the snowplow and vehicle. In the case of mounting the snowplow to a low vehicle height, the pipe bracket height can be adjusted as shown in Fig. 12. In the case of mounting the snowplow to a high vehicle height, it can be also adjusted and is designed as a pinion type adjustment. By using this design, it was convenient to install the snowplow onto the vehicle.

Fig. 12 
Explanation of mounting method between snowplow and vehicle

Fig. 13 shows the explanation of the ready state between the snowplow and moving die for vehicle mounting. Spinning wheels were used and mounted for 360 degree rotation. This was designed to easily connect the snowplow pin to the vehicle hole by moving the handle operating up and down for the snowplow insert.

Fig. 13 
Explanation of ready state between snowplow and moving die for vehicle mounting

Fig. 14 is the photograph that shows snowplow as it is moved toward the vehicle on the rolling cradle by a man in order to connect together. As a result of measuring a mounting time commissioned by the KIMM (Korean Institute of Machinery and Materials), it took only 69 second from mounting initiation until to the blade pin insert and normal operation.

Fig. 14 
Photo of snowplow mounting start with moving die